PlaySudoku.us
Easy · Puzzle #791
1
7
4
6
9
3
8
4
9
6
1
6
2
3
8
7
5
8
7
2
1
8
5
4
7
9
6
3
7
6
3
4
1
9
1
4
2
3
8
5
1
3
9
4
3
7
4
2
6
8
Scan by digit rather than by cell: find everywhere '7' must go before switching to '8'.
Scan by digit rather than by cell: find everywhere '7' must go before switching to '8'.
The hardest Sudoku puzzles require techniques equivalent to propositional logic — the same foundation used in computer proofs.
The hardest Sudoku puzzles require techniques equivalent to propositional logic — the same foundation used in computer proofs.